Litterfall and Fine Woody Debris
Quantifying production of litterfall and fine woody debris is required to estimate annual above-ground net primary productivity at plot, site, and continental scales, and provides essential data for understanding vegetative carbon fluxes over time.  Litter traps are deployed in pairs, one elevated (70 cm x 70 cm x 80 cm, 0.8 m tall) and one ground trap (3 m x 0.5 m) per pair.  Litterfall and fine woody debris production at SRER are estimated using one set of paired traps in two randomly selected locations in each Tower Plot (n = 18).  Elevated litter traps are designed to be large enough that the average size of abundant foliage and fine woody debris elements are easily intercepted by the trap.   Ground traps are intended to intercept particularly large foliage elements that will not fit in elevated traps, and fine woody debris pieces that are too long to be sampled in elevated traps including small diameter branches.  Elevated litter trap samples are collected year-round on a monthly basis, while ground trap samples are collected annually.  Plant litter is sorted into functional groups, which are dried and weighed to determine net primary production.